from OCC.Core.BRepPrimAPI import BRepPrimAPI_MakeBox
from OCC.Display.SimpleGui import init_display

display, start_display, add_menu, add_function_to_menu = init_display()

my_box = BRepPrimAPI_MakeBox(10.,20.,30.).Shape()

display.DisplayShape(my_box, update=True )
start_display()